1. Field of the Invention
The invention relates in general to an image display apparatus, and more particularly to a timing controller for image display and an associated control method.
2. Description of the Related Art
FIG. 1 shows a schematic diagram of a panel display system 100. An image signal 112 outputted from a display controller 110 first enters a timing controller 120. The timing controller 120 converts the image signal 112 to a converted image signal compliant to a predetermined specification according to a display panel 130 having various specifications.
The converted image signal 122 includes gate driving signals of gate drivers and source driving signals of source drivers on the display panel 130 as well as various synchronization signals. The synchronization signals include a horizontal synchronization signal and a vertical synchronization signal. According to data signals between two pulses of the horizontal synchronization signal, data signals outputted from the source drivers may display an image of one display line on the display panel 130. Similarly, according to data signals between two pulses of the vertical synchronization signal, the data signals outputted from the source drivers may display an image of one frame on the display panel. In other words, the display panel 130 displays an image according to the converted image signal generated by the timing controller 120.
The transmittance of liquid crystals in the display panel 130 is determined by rotational angles of the liquid crystals, and the rotational angles of the liquid crystals in pixels are controlled by the source signals in the converted image signal 122. However, as the rotational speeds of liquid crystals are rather slow, an overdrive circuit is designed in the timing controller 120. One main purpose of the overdrive circuit is to compare image differences of two successive frames to modify the source signals in the converted image signal in the aim of accelerating the rotational speeds of liquid crystals in pixels to provide a sharper display image.
When the panel display system 100 presents a display image, the image signal 110 generated by the display controller 110 is constantly inputted into the timing controller 120, which also constantly outputs the converted image signal. To better compare differences between two successive frames in real-time, the overdrive circuit needs to be connected to a memory that temporarily stores data of the previous frame (a first frame). Only when the data of the current frame (a second frame) is inputted into the overdrive circuit, the overdrive circuit can then compare the images in the two successive frames in real-time to generate the converted image signal 122.
As the data of the current frame (the second frame) is temporarily stored in the memory, the data of the previous frame (the first frame) is deleted. When the data of a next frame (a third frame) in the image signal 112 enters the overdrive circuit, the same operation is repeated.
However, if the timing controller 120 encounters signal drifts between the memory and the overdrive circuit, the overdrive circuit will access erroneous data from the memory. As such, the converted image signal 122 outputted will result in an image glitch or even an image crash.
Some reasons causing signal drifts are manufacturing process drifts, voltage drifts or temperature variations, i.e., commonly referred to as a process voltage temperature (PVT) effect.
During a multi-chip package process of memories, due to slight differences in memories made by different memory manufacturers, signal mismatch between memory interfaces may be resulted. Hence, a conventional solution may fail to identify an optimal phase for accessing frame data from a memory.
In a worse scenario, when the timing controller 120 experiences electrostatic discharge (ESD), the data that the timing controller 120 fetches from the memory may be changed into erroneous data, to even crash the panel display system 100 in severe situations.